A high-resolution and high-uniformity fiber image inverter and its preparation method and application

Abstract

The present invention discloses a high-resolution and high-uniformity fiber optic image inverter and its preparation method and application. The preparation method includes: preparing single filaments and sleeve light-absorbing filaments: matching a core material glass rod with a high refractive index and a cladding glass tube with a low refractive index and then performing single-filament drawing to obtain the drawn single filaments, where the filament diameter of the single filaments is Φ2.8 - 4.0 mm; matching a light-absorbing material glass rod and a cladding glass tube with a low refractive index and then drawing them into sleeve light-absorbing filaments, where the filament diameter of the sleeve light-absorbing filaments is the same as that of the single filaments; performing primary multi-filament drawing; performing secondary multi-filament drawing; hot melt pressing and twisting forming. The fiber optic image inverter has a transmittance > 70% and a transmittance uniformity < 5% in the wavelength range of 400 - 700 nm. The fiber optic image inverter can be applied to low-light level image intensifiers.

Description

Technical Field

[0001] The invention relates to the field of manufacturing optical fiber image transmission elements, and in particular to a high-resolution and high-uniformity optical fiber image invertor and a preparation method and application thereof. Background Art

[0002] The high definition of low-light night vision devices includes high resolution and high contrast. The benefit of continuously improving resolution is that more details can be seen, and the improvement of contrast can make the image clearer and more eye-catching. Among them, the impact of contrast on visual effects is very critical. Contrast refers to the degree of contrast between light and dark in the picture. Increasing contrast will make the bright areas in the picture brighter and the dark areas darker, and the contrast between light and dark will be enhanced; the greater the contrast, the clearer and more eye-catching the image will be, while a small contrast will make the entire image gray. High contrast is of great help to the clarity and detail of the image. There are two ways to improve contrast: one is to increase the brightness to increase the contrast. This method is relatively simple, but it is limited by the life of the image tube, light leakage of components, etc. The brightness cannot be increased indefinitely, and the virtual high brightness will also cause the image to be distorted due to high brightness, bringing bad effects; the second is to make the black darker and reduce the minimum brightness to make the contrast between light and dark more obvious. Therefore, whether the low-light-level night vision device can capture sufficiently clear details has a lot to do with the resolution and contrast of the fiber-optic imaging element. Contrast is an important performance indicator of fiber-optic imaging products. At present, the contrast of fiber-optic imaging elements on the market can only reach 3-5%. With the continuous development of fiber-optic imaging technology, the requirements for various product performances are getting higher and higher, and the fiber-optic image inverter is the key material to ensure the imaging quality of the low-light-level night vision device.

[0003] The image transmission mechanism of the fiber optic image inverter is realized by utilizing the total reflection principle of the optical fiber. The optical fiber constituting the fiber optic image inverter is prepared by hot melting and pressing a low-refractive-index skin glass tube, a high-refractive-index core glass rod, and a light-absorbing glass filament by utilizing a rod-tube combination and a vacuum drawing process. Since the optical fiber is completely tightly fused together by the skin glass, the adjacent optical fibers are close to each other, resulting in cross-talk between adjacent fibers. For example, due to the uneven temperature field or uneven drawing force during the preparation process, the uneven thickness of the skin glass tube may cause the input light to penetrate the skin during the total reflection process, resulting in light penetration and light leakage. Alternatively, the contact interface of the core or skin of the optical fiber destroys the total reflection condition of light due to defects or contaminants, causing light scattering. These scattered lights enter adjacent fibers and also cause cross-talk, which is an important factor directly affecting the contrast and clarity of the imaging quality of the optical fiber image transmission element.

[0004] To solve the problem of light crosstalk in fiber optic inverters, it is usually adopted to fill the gaps between adjacent optical fibers with light-absorbing glass filaments to absorb stray light and reduce light crosstalk. The method of inserting absorption filaments can effectively eliminate stray light. The light-absorbing glass material is drawn into absorption filaments and inserted into the gaps between the arranged optical fibers, thus playing a role in absorbing crosstalk, leakage light, etc. However, complete optical insulation cannot be achieved, and the key lies in the problem of light-absorbing glass. The function of the light-absorbing glass material is to absorb the stray light that penetrates the cortex of the optical fiber to achieve optical insulation and improve the contrast of the image. Light-absorbing glass is an important type of optical glass, mainly achieving the absorption effect of interfering stray light and improving the performance of optical components such as clarity and contrast. However, with the expansion of application fields, in recent years, there have been increasing requirements for ultra-thin, high clarity, and high contrast, so it is also required that the light-absorbing glass has better light absorption effect, more thorough absorption of stray light, and coverage of the wavelength range from ultraviolet to visible to near-infrared.

[0005] Ordinary light-absorbing glass materials still have a relatively high transmittance in the visible light range at a thickness of 0.5 mm. As the thickness decreases, the transmittance will gradually increase. The light-absorbing materials of traditional fiber optic image transmission components generally have problems such as low efficiency of absorbing stray light and poor imaging contrast. Especially for the light-absorbing glass used in fiber optic image transmission components, since the existing light-absorbing glass materials will easily diffuse into the cortical glass after the fiber filament diameter is drawn to less than or equal to 4.0 μm, ion penetration occurs between the glasses, and even blackening appears at the edges of the fiber optic inverter after twisting or fixed pattern noise defects such as white chicken wires and multi-filament shadows occur, resulting in very low quality and finished product qualification rate of the fiber optic inverter and being unable to meet the mass application requirements of high-definition fiber optic image transmission components. The main reason for this is that the light absorption ability of the light-absorbing glass material and the fixed pattern noise defect are a pair of contradictions. The stronger the light absorption ability of the light-absorbing glass, the greater the probability of generating fixed pattern noise defects. If the light absorption ability of the light-absorbing glass is too weak, the effect of improving the contrast of the fiber optic inverter cannot be achieved. Summary of the Invention

[0006] The object of the present invention is to provide a preparation method of a high-resolution and high-uniformity fiber optic inverter that can improve the resolution and clarity of the imaging of the fiber optic inverter in view of the above technical problems.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A preparation method of a high-resolution and high-uniformity fiber optic inverter, comprising:

[0009] (1) Preparation of single filaments and sleeve light-absorbing filaments: After matching a core glass rod with a high refractive index and a cladding glass tube with a low refractive index, single filaments are drawn, and the drawn single filaments have a filament diameter of Φ2.8 - 4.0 mm; after matching a light-absorbing material glass rod and a cladding glass tube with a low refractive index, sleeve light-absorbing filaments are drawn, and the filament diameter of the sleeve light-absorbing filaments is the same as that of the single filaments;

[0010] (2) Primary multifilament drawing: The drawn single filaments are arranged into a hexagonal prism with a regular hexagonal cross-section. In the hexagonal prism, the number of single filaments on each side is 6, and the total number of single filaments in the hexagonal prism arranged by single filaments is 91. Then, 1 sleeve light-absorbing filament is used to replace the single filament at the very center of the arranged regular hexagon to obtain a primary composite rod, and then the primary composite rod is drawn into a primary multifilament. The distance between opposite sides of the regular hexagon of the primary multifilament is 1.14 - 1.26 mm;

[0011] (3) Secondary multifilament drawing: The primary multifilament is arranged into a secondary composite rod with a regular hexagonal cross-section. The number of primary multifilaments on each side of the rod arrangement is 12 - 17. The secondary composite rod is drawn into a secondary multifilament. The distance between opposite sides of the regular hexagon of the secondary multifilament is 0.86 - 1.30 mm. Then, the secondary multifilament is cut to a fixed length and arranged into plate segments;

[0012] (4) Hot melt pressing and forming: The arranged plate segments are placed into a hot melt pressing and forming mold. The mold loaded with the plate segments is placed into a hot melt pressing and forming furnace at a first preset temperature, and then the mold is pressed according to the designed compression ratio to obtain a blank of an optical fiber plate of a high-uniformity fiber optic image inverter with a unit filament diameter ≤ 4.0 μm;

[0013] (5) Twisting and forming: The obtained blank of the optical fiber plate is processed and twisted by 180° to obtain a high-resolution and high-uniformity fiber optic image inverter.

[0014] The first preset temperature is 450 - 550 °C.

[0015] The pressing time of the hot melt pressing and forming is controlled within 130 - 180 minutes.

[0016] The light-absorbing glass rod is made of light-absorbing glass, and the light-absorbing glass is composed of the following components in mole percentage: SiO2 71 - 80.0%, Al2O3 0.5 - 5.0%, B2O3 1.0 - 5.0%, Na2O 1.0 - 11.0%, K2O 6.0 - 11.0%, MgO 0.1 - 2.0%, CaO 0.1 - 2.0%, BaO 0 - 0.04%, TiO2 0 - 1.0%, Co2O3 0.1 - 0.4%, NiO 0.1 - 1.0%, MnO 1.0 - 5.0%, V2O5 0.1 - 1.0%, CeO2 0 - 0.2%, CuO 0 - 0.05%.

[0017] Preferably, the light-absorbing glass is composed of the following components in mole percentage:

[0018]

[0019]

[0020] More preferably, the light-absorbing glass is composed of the following components in mole percentage:

[0021]

[0022] The present invention also provides a method for preparing light-absorbing glass for a high-resolution and high-uniformity fiber optic image inverter using the said composition, comprising the following steps:

[0023] (1) Raw material preparation: Weigh quartz sand, alumina, boric acid or boric anhydride, sodium carbonate, potassium carbonate, basic magnesium carbonate, calcium carbonate, barium carbonate, titanium dioxide, cobalt sesquioxide, nickel monoxide, manganese monoxide, vanadium pentoxide, cerium oxide and copper oxide according to the ratio, and mix them evenly to obtain a raw material mixture;

[0024] (2) Glass melting: Put the raw material mixture into a crucible for melting. After the raw material mixture is melted and clarified, pour the melted and clarified glass liquid into a preheated mold to form a specified specification. After the glass liquid cools and solidifies, light-absorbing glass is obtained; the melting process includes melting at a temperature of 1450 - 1550 °C for 7 - 10 hours, and the raw material mixture is stirred 2 - 3 times during the melting process. The clarification process includes clarifying at a temperature of 1350 - 1450 °C for 2 - 4 hours.

[0025] The light-absorbing glass of the present invention has strong and uniform light absorption ability and spectral absorption effect in the wavelength range of 510 - 660 nm at a thickness of 0.5 ± 0.01 mm, and the spectral transmittance ≤ 3.0%; the thermal expansion coefficient of the light-absorbing glass of the present invention is (85 ± 5) × 10 -7 / ℃, and kept warm at 850-900℃ for 6 hours without crystallization or phase separation.

[0026] The invention also provides a high-resolution and high-uniformity optical fiber image invertor, which is prepared according to the preparation method.

[0027] The present invention further provides an application of the high-resolution and high-uniformity optical fiber image invertor in a low-light-level image intensifier.

[0028] In the light absorbing glass composition of the present invention, SiO2 is the main component of the glass skeleton and plays a major role in the glass skeleton. The molar percentage (mol.%) of SiO2 is 71.0-80.0. When the SiO2 content is lower than 71.0 mol.%, it is difficult to obtain a thermal expansion coefficient similar to that of the leather glass, and the chemical resistance of the glass will be reduced; when the SiO2 content is higher than 80.0 mol.%, the high temperature viscosity of the glass will increase, resulting in an excessively high melting temperature of the glass.

[0029] Al2O3 is an intermediate oxide of glass. 3+ There are two coordination states, namely, located in tetrahedron or octahedron. When there is enough oxygen in the glass, aluminum oxygen tetrahedron [AlO4] is formed, forming a continuous network with silicon oxygen tetrahedron. When there is insufficient oxygen in the glass, aluminum oxygen octahedron [AlO6] is formed, which is an external body of the network and is located in the cavities of the silicon oxygen structure network. Therefore, within a certain content range, it can be the main body of the glass network formed with SiO2. The molar percentage (mol.%) of Al2O3 is 0.5-5.0. Al2O3 content greater than 5.0 mol.% will significantly increase the high temperature viscosity of the glass and increase the melting temperature of the glass.

[0030] B2O3 is a glass-forming oxide and a component of the glass skeleton. It is also a flux that reduces the viscosity of the glass. Boron oxide triangles [BO3] and boron oxide tetrahedrons [BO4] are structural components. Boron may exist in the form of triangles [BO3] or boron oxide tetrahedrons [BO4] under different conditions. Under high-temperature melting conditions, it is generally difficult to form boron oxide tetrahedrons, and can only exist in the form of trihedrons. However, at low temperatures, under certain conditions, B 3+ It has a tendency to capture free oxygen to form tetrahedrons, making the structure compact and increasing the low-temperature viscosity of the glass. However, due to its characteristics of reducing the viscosity of the glass at high temperatures and increasing the viscosity of the glass at low temperatures, it is also the main component that reduces the refractive index of the glass, which determines that its content range is relatively small. The molar percentage (mol.%) of B2O3 is 1.0-5.0. If the content of B2O3 is greater than 5.0mol.%, the phase separation tendency of the glass will increase.

[0031] Na2O is an external oxide of the glass structure network. The molar percentage (mol.%) of Na2O is 1.0 - 11.0. When the content of Na2O is greater than 11.0 mol.%, it will increase the thermal expansion coefficient of the glass.

[0032] K2O is an external oxide of the glass structure network. The molar percentage (mol.%) of K2O is 6.0 - 11.0. When the content of K2O is greater than 11.0 mol.%, it will increase the thermal expansion coefficient of the glass.

[0033] MgO is an external oxide of the glass structure network and is used to adjust the crystallization temperature of the glass. The molar percentage (mol.%) of MgO is 0.1 - 2.0. When the content of MgO is greater than 2.0 mol.%, it will increase the crystallization tendency of the glass.

[0034] CaO is an external oxide of the glass structure network. The molar percentage (mol.%) of CaO is 0.1 - 2.0. When the content of CaO is greater than 2.0 mol.%, it will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0035] BaO is an external oxide of the glass structure network and is used to adjust the crystallization temperature of the glass. The molar percentage (mol.%) of BaO is 0 - 0.04. When the content of BaO is greater than 0.04 mol.%, it will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0036] TiO2 is used to adjust the chemical stability and crystallization of the glass. The molar percentage (mol.%) of TiO2 is 0 - 1.0. When the content of TiO2 is greater than 1.0 mol.%, it will reduce the chemical resistance of the glass and increase the crystallization tendency.

[0037] Co2O3 is a colorant for light-absorbing glass. The molar percentage (mol.%) of Co2O3 is 0.1 - 0.4. Co2O3 has a lower melting point than CoO, enabling Co2O3 to combine with other coloring ions to form a stable form in the glass, thereby making the coloring of the light-absorbing material more stable. When the content of Co2O3 is greater than 0.4 mol.%, it will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0038] NiO is a colorant for light-absorbing glass. The molar percentage (mol.%) of NiO is 0.1 - 1.0, and Ni 2+ has a good absorption effect in the visible light region. When the content of NiO is greater than 1.0 mol.%, it will reduce the chemical stability of the glass and increase the crystallization tendency of the glass.

[0039] MnO is a colorant for light-absorbing glass. In the present invention, MnO is the main light absorber. MnO has a higher melting point temperature than MnO2, and Mn 2+ has a stable light absorption ability between 400 - 700 nm and can form stable coloring in the glass. The molar percentage (mol.%) of MnO is 1.0 - 5.0. When the content of MnO is greater than 5.0 mol.%, the chemical stability of the glass will be reduced and the crystallization tendency of the glass will increase.

[0040] V2O5 is a colorant for light-absorbing glass. The molar percentage (mol.%) of V2O5 is 0.1 - 1.0. V2O5 can solidify the coloring of manganese ions, thus making the light-absorbing material more stable in coloring. When the content of V2O5 is greater than 1.0 mol.%, the chemical stability of the glass will be reduced and the crystallization tendency of the glass will increase.

[0041] CeO2 is a rare earth oxide, mainly regulating the crystallization performance of the glass and acting as a glass fining agent. The molar percentage (mol.%) of CeO2 is 0 - 0.2. When the content of CeO2 is greater than 0.2 mol.%, the crystallization tendency of the glass will increase.

[0042] CuO is a colorant for light-absorbing glass and can combine with Ni 2+ 、Co 3+ 、Mn 2+ etc. to form stable coloring in the glass. By using the composite absorption effect, it can ensure the absorption of stray light in the wavelength range of 400 nm - 700 nm, obtain a better light absorption effect, and make the light absorption curve not show obvious transmission peaks in the visible light region. The molar percentage (mol.%) of CuO is 0 - 0.05. However, when the content of CuO is greater than 0.05 mol.%, the crystallization tendency of the glass will increase.

[0043] The light-absorbing glass of the present invention has good chemical stability and anti-crystallization performance. After the light-absorbing glass is melted, there are no stones, no bubble holes inside. When applied to the fiber image inverter, it can effectively improve the absorption of stray light between optical fibers to reduce the crosstalk between fibers, thereby achieving the effect of improving the contrast and clarity of the imaging of the fiber image inverter. The obtained fiber image inverter has the characteristics of high resolution and high uniformity.

[0044] Compared with the prior art, the beneficial effects of the high-resolution and high-uniformity fiber image inverter provided by the present invention are:

[0045] (1) The crosstalk of the high-uniformity fiber image inverter is less than 1.0% at a distance of 0.1 mm from the knife edge;

[0046] (2) The central resolution of the high-uniformity fiber image inverter is greater than 140 lp / mm;

[0047] (3) This high-uniformity fiber image inverter has excellent fixed-pattern noise performance and no obvious multifilament boundaries are observed under a 10x microscope;

[0048] (4) This high-uniformity fiber image inverter has a transmittance > 70% in the wavelength range of 400 - 700 nm, a transmittance uniformity < 5%, few spot defects, and no aggregated spot defects.

[0049] (5) Applying the light-absorbing glass of the present invention to the fiber image inverter can effectively improve the absorption of stray light between optical fibers to reduce crosstalk between fibers, thereby achieving the effect of enhancing the contrast and clarity of the image formed by the fiber image inverter.

[0050] Through the insertion and adjustment of the sleeve light-absorbing filaments in the present invention, the difficulty of the preparation process is reduced, the resolution of the fiber image inverter is improved, such that the central resolution of the fiber image inverter is greater than 140 lp / mm, and the contrast of the fiber image inverter is increased, such that the crosstalk at a distance of 0.1 mm from the knife edge is less than 1%. Thus, a fiber image inverter with high resolution and high uniformity is prepared. The high-resolution and high-uniformity fiber image inverter of the present invention has the advantages of less stray light crosstalk, good internal structure uniformity, high resolution, high contrast, and a simple preparation process. Description of the Drawings

[0051] Figure 1 It is a schematic diagram of the internal structure of the optical fiber of the high-resolution and high-uniformity fiber image inverter provided by an embodiment of the present invention;

[0052] Figure 2 It is the transmittance curve of the light-absorbing glass provided by an embodiment of the present invention.

[0053] Among them, 1 is the sleeve light-absorbing filament, 2 is the skin glass, and 3 is the core glass. Detailed Embodiments

[0054] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe in detail the embodiments of the present invention with reference to the drawings.

[0055] Refer to Figure 1 , which is a schematic diagram of the internal structure of the optical fiber of the high-resolution and high-uniformity fiber image inverter provided by an embodiment of the present invention. A single filament is composed of the skin glass 2 and the core glass 3 located in the skin glass 2. After arranging 6 single filaments per side to form a primary composite rod with a regular hexagon cross-section, 1 single filament arranged at the very center in the hexahedron primary composite rod is replaced with the sleeve light-absorbing filament 1, and the above-completed primary composite rod is drawn into a primary multifilament as shown in Figure 1 shown.

[0056] Refer to Figure 2, is the transmittance curve of the light absorption material. It can be seen therefrom that in the wavelength range of 510 - 660 nm, it has a strong and uniform light absorption ability and spectral absorption effect, and the spectral transmittance ≤ 3.0%. It can be seen that the light absorption effect on visible light is very obvious.

[0057] In this article, all "mole percentages mol.%" are based on the total molar amount of the final glass composition. The glass chemical compositions (mol.%) of the examples are listed in detail in Table 1.

[0058] The parameters measured for the light absorption material glass of the present invention, as well as the measurement methods and instruments, are as follows:

[0059] (1) The transmittance of the glass is measured using a transmittance tester;

[0060] (2) The average linear thermal expansion coefficient α in the range of 30 - 300 °C 30 / 300 [×10 -7 / °C] is measured using a horizontal dilatometer and measured by the method specified in GB / T 16920 - 2015.

[0061] Table 1 Chemical compositions (mol.%) and properties of the light absorption material glass examples

[0062]

[0063]

[0064] Example 1

[0065] A preparation method of a high-resolution and high-uniformity fiber image inverter includes the following steps:

[0066] (1) Referring to the glass composition of Example 1 in Table 1, prepare a light absorption material glass rod;

[0067] (2) Drawing of single filaments and light absorption filaments: After matching a core material glass rod with a high refractive index and a cladding glass tube with a low refractive index, draw single filaments to obtain drawn single filaments with a filament diameter of Φ3.2 mm; After matching a light absorption material glass rod and the cladding glass tube with a low refractive index, draw them into a sleeve light absorption filament, and the filament diameter of the sleeve light absorption filament is the same as that of the single filament;

[0068] (3) First-stage multifilament drawing: Arrange the drawn single filaments into a hexagonal prism with a regular hexagonal cross-section. In the hexagonal prism, the number of single filaments on each side is 6, and the total number of single filaments in the hexagonal prism arranged is 91. Replace the single filament at the very center of the arranged hexagonal prism with 1 sleeve light absorption filament to obtain a first-stage composite rod, and then draw the first-stage composite rod into a first-stage multifilament. The opposite side dimension of the regular hexagon of the first-stage multifilament is 1.14 mm;

[0069] (4) Secondary multifilament drawing: Rearrange the primary multifilament into a secondary composite rod with a regular hexagon cross-section. The number of filaments on each side of the primary multifilament arrangement rod is 14, and the total number of filaments in the primary multifilament arrangement rod is 547. Then draw the secondary composite rod into a secondary multifilament. The distance between opposite sides of the regular hexagon of the secondary multifilament is 1.06 mm. After that, cut the secondary multifilament to a fixed length and arrange it into plate segments;

[0070] (5) Hot melt pressing and forming: Put the plate segments into a hot melt pressing and forming mold, and put the mold with the plate segments into a hot melt pressing and forming furnace at a high temperature of 500 °C. Then start pressing the plate according to the designed compression ratio. The time for hot melt pressing and forming is controlled at 150 minutes, and a blank optical fiber plate of a high uniformity fiber optic image inverter with a unit filament diameter of 3.94 μm is obtained;

[0071] (6) Twisting and forming: Process the obtained blank optical fiber plate, and perform twisting and forming at an angle of 180°, then a high-resolution and high-uniformity fiber optic image inverter can be obtained.

[0072] Example 2

[0073] A preparation method of a high-resolution and high-uniformity fiber optic image inverter, comprising the following steps:

[0074] (1) Refer to the glass composition in Example 2 of Table 1 to prepare a light absorption material glass rod;

[0075] (2) Drawing of single filaments and light absorption filaments: Match a core material glass rod with a high refractive index and a cladding glass tube with a low refractive index and then perform single filament drawing to obtain the drawn single filaments. The filament diameter of the single filaments is Φ2.8 mm; Match the light absorption material glass rod and the cladding glass tube with a low refractive index and then draw them into sleeve light absorption filaments. The filament diameter of the sleeve light absorption filaments is the same as that of the single filaments;

[0076] (3) Primary multifilament drawing: Arrange the drawn single filaments into a hexahedron with a regular hexagon cross-section. In the hexahedron, the number of single filaments on each side is 6, and the total number of single filaments in the hexahedron arranged is 91. Then replace the single filament at the very center of the arranged hexahedron with 1 sleeve light absorption filament to obtain a primary composite rod. Then draw the primary composite rod into a primary multifilament. The distance between opposite sides of the regular hexagon of the primary multifilament is 1.26 mm;

[0077] (4) Secondary multifilament drawing: Rearrange the primary multifilament into a secondary composite rod with a regular hexagon cross-section. The number of filaments on each side of the primary multifilament arrangement rod is 12, and the total number of filaments in the primary multifilament arrangement rod is 397. Then draw the secondary composite rod into a secondary multifilament. The distance between opposite sides of the regular hexagon of the secondary multifilament is 0.86 mm. After that, cut the secondary multifilament to a fixed length and arrange it into plate segments;

[0078] (5)Hot melt pressing forming: Put the plate section into the hot melt pressing forming die, place the die with the plate section in the hot melt pressing furnace at a high temperature of 450 °C, and then start pressing the plate according to the designed compression ratio. Control the hot melt pressing forming time at 130 minutes to obtain the optical fiber plate blank of the high-definition fiber optic inverter with a unit wire diameter of 3.97 μm;

[0079] (6)Twisting forming: Process the obtained optical fiber plate blank and perform twisting forming at an angle of 180°, then the high-resolution and high-uniformity fiber optic inverter can be obtained.

[0080] Example 3

[0081] (1)Refer to the glass composition in Example 3 of Table 1 to prepare the light-absorbing material glass rod;

[0082] (2)Drawing of single filaments and light-absorbing filaments: Match the high-refractive-index core material glass rod and the low-refractive-index cladding glass tube and perform single-filament drawing to obtain the drawn single filaments, and the wire diameter of the single filaments is Φ4.0 mm; Match the light-absorbing material glass rod and the low-refractive-index cladding glass tube and draw them into a sleeve light-absorbing filament, and the wire diameter of the sleeve light-absorbing filament is the same as that of the single filaments;

[0083] (3)Arrange the drawn single filaments into a hexagonal prism with a regular hexagonal cross-section. In the hexagonal prism, the number of single filaments on each side is 6, and the total number of single filaments in the arranged hexagonal prism is 91. Replace the single filament at the very center of the arranged hexagonal prism with 1 sleeve light-absorbing filament to obtain a primary composite rod, and then draw the primary composite rod into a primary composite filament. The opposite side dimension of the regular hexagon of the primary composite filament is 1.18 mm;

[0084] (4)Drawing of secondary composite filaments: Arrange the primary composite filaments into a secondary composite rod with a regular hexagonal cross-section. The number of primary composite filaments on each side of the rod arrangement is 17, and the total number of primary composite filaments in the rod arrangement is 817. Draw the secondary composite rod into a secondary composite filament. The opposite side dimension of the regular hexagon of the secondary composite filament is 1.30 mm. Then, after cutting the secondary composite filament to a fixed length, arrange it into a plate section;

[0085] (5)Hot melt pressing forming: Put the plate section into the hot melt pressing forming die, place the die with the plate section in the hot melt pressing furnace at a high temperature of 550 °C, and then start pressing the plate according to the designed compression ratio. Control the hot melt pressing forming time at 180 minutes to obtain the optical fiber plate blank of the high-definition fiber optic inverter with a unit wire diameter of 3.96 μm;

[0086] (6)Twisting forming: Process the obtained optical fiber plate blank and perform twisting forming at an angle of 180°, then the high-resolution and high-uniformity fiber optic inverter can be obtained.

[0087] Example 4

[0088] The actual composition of the light-absorbing glass refers to the composition of Example 4 in Table 1, and a high-resolution and high-uniformity fiber image inverter is prepared by the same method as in Example 1.

[0089] Example 5

[0090] The actual composition of the light-absorbing glass refers to the composition of Example 5 in Table 1, and a high-resolution and high-uniformity fiber image inverter is prepared by the same method as in Example 1.

[0091] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-resolution and high-uniformity fiber image inverter, characterized in that, Including: (1) Preparing single filaments and sleeve light-absorbing filaments: After matching a core glass rod with a high refractive index and a cladding glass tube with a low refractive index, single filaments are drawn, and the drawn single filaments have a filament diameter of Φ2.8 - 4.0 mm; after matching a light-absorbing material glass rod and a cladding glass tube with a low refractive index, sleeve light-absorbing filaments are drawn, and the filament diameter of the sleeve light-absorbing filaments is the same as that of the single filaments; (2) First-stage multifilament drawing: The drawn single filaments are arranged into a hexagonal prism with a regular hexagonal cross-section. In the hexagonal prism, the number of single filaments on each side is 6, and the total number of single filaments in the hexagonal prism arranged by single filaments is 91. Then, 1 sleeve light-absorbing filament is used to replace the single filament at the very center of the arranged regular hexagon to obtain a first-stage composite rod, and then the first-stage composite rod is drawn into a first-stage multifilament. The opposite-side dimension of the regular hexagon of the first-stage multifilament is 1.14 - 1.26 mm; (3) Second-stage multifilament drawing: The first-stage multifilament is arranged into a second-stage composite rod with a regular hexagonal cross-section. The number of multifilaments arranged on each side of the rod of the first-stage multifilament is 12 - 17. The second-stage composite rod is drawn into a second-stage multifilament. The opposite-side dimension of the regular hexagon of the second-stage multifilament is 0.86 - 1.30 mm. Then, the second-stage multifilament is cut to a fixed length and arranged into plate segments; (4) Hot melt pressing and forming: The arranged plate segments are placed into a hot melt pressing and forming mold. The mold loaded with the plate segments is placed into a hot melt pressing and forming furnace at a first preset temperature, and then the plate is pressed according to the designed compression ratio to obtain a blank of an optical fiber plate of a high-uniformity fiber optic image inverter with a unit filament diameter ≤ 4.0 μm; (5) Twisting and forming: The obtained blank of the optical fiber plate is processed and twisted and formed at an angle of 180° to obtain a high-resolution and high-uniformity fiber optic image inverter; The light-absorbing material glass rod is prepared from light-absorbing material glass, and the light-absorbing material glass is composed of the following components in molar percentage: SiO2 71 - 80.0%, Al2O3 0.5 - 5.0%, B2O3 1.0 - 5.0%, Na2O 1.0 - 11.0%, K2O 6.0 - 11.0%, MgO 0.1 - 2.0%, CaO 0.1 - 2.0%, BaO 0 - 0.04%, TiO2 0 - 1.0%, Co2O3 0.1 - 0.4%, NiO 0.1 - 1.0%, MnO 1.0 - 5.0%, V2O5 0.1 - 1.0%, CeO2 0 - 0.2%, CuO 0 - 0.05%.

2. The preparation method of the high-resolution and high-uniformity fiber image inverter according to claim 1, wherein, The first preset temperature is 450 - 550 °C.

3. The preparation method of the high-resolution and high-uniformity fiber image inverter according to claim 1, characterized in that, The pressing time of the hot melt pressing and forming is controlled within 130 - 180 minutes.

4. The method for preparing a high-resolution and high-uniformity fiber image inverter according to claim 1, characterized in that The light-absorbing material glass is composed of the following components in molar percentage:

5. The preparation method of the high-resolution and high-uniformity fiber image inverter according to claim 4, characterized in that, The light-absorbing material glass is composed of the following components in molar percentage:

6. The preparation method of the high-resolution and high-uniformity fiber image inverter according to claim 1, characterized in that, The preparation method of the light-absorbing material glass includes the following steps: (1) Raw material preparation: Weigh quartz sand, alumina, boric acid or boric anhydride, sodium carbonate, potassium carbonate, basic magnesium carbonate, calcium carbonate, barium carbonate, titanium dioxide, cobalt sesquioxide, nickel monoxide, manganese monoxide, vanadium pentoxide, cerium oxide and copper oxide according to the ratio, and mix them evenly to obtain a raw material mixture; (2) Glass melting: Put the raw material mixture into a crucible for melting. After the raw material mixture is melted and clarified, pour the melted and clarified glass liquid into a preheated mold to form a specified specification. After the glass liquid cools and solidifies, obtain the light absorption material glass; The melting process includes melting at a temperature of 1450 - 1550 °C for 7 - 10 hours, and the raw material mixture is stirred 2 - 3 times during the melting process. The clarification process includes clarifying at a temperature of 1350 - 1450 °C for 2 - 4 hours.

7. The preparation method of the high-resolution and high-uniformity fiber image inverter according to claim 6, characterized in that, The light-absorbing glass has strong and uniform light absorption ability and spectral absorption effect in the wavelength range of 510 - 660 nm at a thickness of 0.5 ± 0.01 mm, and the spectral transmittance ≤ 3.0%; the thermal expansion coefficient of the light-absorbing glass is (85 ± 5) × 10 -7 / ℃; it does not crystallize or phase-separate when kept at 850 - 900 °C for 6 hours.

8. A high-resolution and high-uniformity fiber optic image inverter, characterized in that, Prepared according to the preparation method of the high-resolution and high-uniformity fiber image inverter described in any one of claims 1 - 7.

9. Application of the high-resolution and high-uniformity fiber image inverter described in claim 8 in a low-light image intensifier.

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